California Hazel grows in the following 4 states and provinces:

Information about California Hazel:

The Corylus Cornuta Var. Californica is commonly known as the California Filbert, California Hazel as well as California Hazelnut.

The accepted scientific name for California hazelnut is Corylus cornuta
Marsh. var. californica (A. DC.) Sharp . The genus Corylus
comprises 15 species, most of which occur in Asia. Beaked hazelnut
(Corylus cornuta) is the only species native to the United States .
Beaked hazelnut is distributed across North America. California hazelnut
is the Pacific Coast entity of the species ; beaked hazelnut is a shrub
occupying the eastern range of the species . There are two recognized
forms of California hazelnut :

California hazelnut occurs in California, Oregon, Washington, and British
Columbia . In California it occurs along the Coast Range from Santa
Cruz County northward along the coast to Del Norte County, eastward
through Siskiyou County, and southward in the Sierra Nevada to Tulare
County . In Oregon and Washington it occurs mostly west and
occasionally east of the Cascades . In British Columbia it occurs
on the lower mainland and on Vancouver Island .
Intermediate forms of C. cornuta var. californica x C. cornuta var.
cornuta may occur in the Fraser Canyon and Columbia Forest Region of
British Columbia .
Corylus cornuta var. californica forma glandulosa is frequently found
along the Pacific Coast. It is more frequent than C. cornuta var.
californica forma californica on southern Vancouver Island but becomes
scarcer inland .